As other sources of AMS backgrounds for radiocarbon are reduced or eliminated, sample-to-sample memory in graphitization reactors may become significant. The hydrogen reduction reactors in our laboratory are based on modified 1/4” Ultra Torr tees, Swagelok SS-P4T plug valves, and 6 x 50 mm glass culture tubes, and have a volume of 3.1 cm3. Pressures are monitored with Omega PX139 pressure transducers, and water from the graphitzation reaction is removed by chemical absorption in magnesium perchlorate. The memory effect in these reactors was studied by graphitizing radiocarbon-dead CO2 samples in reactors that had been used previously for samples made from ANU sucrose or 14C-free calcite. Reactor components were systematically removed or replaced to evaluate contributions to the overall memory effect, and several “preconditioning” methods for reducing the problem were evaluated.
See more of Poster Session II
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)